The purpose of this project is to characterize the mechanisms of expression of humoral and cell-mediated immune reactions in the respiratory tract. A canine model was developed and used to compare the functions of pulmonary lymphatic tissue with the functions of systemic lymphocytes. Functional capacities, including immunoglobulin synthesis and mitogen-responsiveness of lymphocytes obtained by bronchial lavage were defined. The experimental conditions of dose, route and time required to induce specific antibody-forming cells to appear in bronchial lavage cells and hilar lymph nodes were characterized. Mechanisms of disposal of a complex organic particulate antigen by the lung and the resultant antibody-mediated immune response to it were characterized. An inbred murine model for detailed analysis of pulmonary immune phenomena was developed. Comparative studies of the antibody-forming cell response of pulmonary and systemic lymphoid tissue to stimulation by sheep erythrocytes via several routes were conducted. Specific reagents for immunofluorescent analysis of surface markers of murine lymphocytes sets and subsets were developed. Studies of the mitogen-responsiveness of pulmonary and systemic lymphocytes were conducted. A microcytolytic assay was developed and the T cell-mediated cytolytic response of pulmonary and systemic lymphocytes to local and systemic immunization with allogeneic cells were performed. Experimental conditions were defined under which cytolytically active cells appeared in pulmonary parenchyma.